This invention relates to a valve timing control apparatus configured to vary a relative rotational phase of a cam shaft with respect to a crank shaft of an internal combustion engine, and to vary a valve timing (opening and closing timing) of an intake valve or an exhaust valve.
U.S. Pat. No. 7,441,524 (corresponding to Japanese Patent Application Publication No. 2005-299640) shows a valve timing control apparatus including a rotational phase sensing section configured to sense a relative rotational phase between a crank shaft and a cam shaft at an arbitrary timing. This valve timing control apparatus is controlled by the rotational phase sensed by the rotational phase sensing section.
This valve timing control apparatus can sense the relative rotational phase even in a period shorter than a rotation period of the cam shaft. The feedback control of the valve timing control can be performed even at the low rotation speed so as to correspond the control period of the valve timing to the detection period of the relative rotational phase. Accordingly, it is possible to attain the high-responsive/high-accurate valve timing control.
That is, in a case in which there is roughness of the detection period of the rotational phase sensing section irrespective of the engine rotation, the phase is separated from the target phase by the overshoot after the arrival to the target phase angle, so that it is adversely affected. Accordingly, the rotational phase sensing section with the high accuracy is used so as to suppress the overshoot, and to improve the control response and the control accuracy.